Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
  • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/50—Partial depolymerisation
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/18—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/38—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising unsaturated nitriles as the major constituent
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
  • C08J2333/18—Homopolymers or copolymers of nitriles
  • C08J2333/20—Homopolymers or copolymers of acrylonitrile

Definitions

• the present invention mainly comprises the heating of a spinning solution of polyacrylonitrile or copolymers of polyacrylonitrile ocntaining a high proportion of polyacrylonitrile, the
• aqueous zinc chloride solutions can be spun so that only i polymer being dissolved in an aqueous solution of zinc chloride or of mixed salts including zinc chloride, for sev'- eral hours to several days, depending upon the temperature used, and also depending upon the pH of the solution as will be further discussed below, until the tendency of the solution to coagulate has been lowered to such extent that the solution can be easily spun to fibers, and then spinning polyacrylonitrile fibers from the solution.
• the treatment step of the present invention wherein the spinning solution is subjected to a heating step for a period of time suflicient to reduce the tendency of the solution to coagulate (which will hereinafter be referred to as lowering of the coagulation point of the solution) will be referred to as a ripening process, and reference will also be made to the degree of ripening of the polymers in the salt solutions.
• the spinning polyacrylonitrile refers not only to homopolymerisates, that is polymerisates formed solely of polyacrylonitrile, but also to copolymers of acrylonitrile with any of the numerous substances with which the same can form copolymers such as acrylic acid, methacrylic acid, methacrylic acid methyl ester, vinyl pyridine, vinyl imidazol, vinyl acetate, etc., in which the percentage of acrylonitrile in the copolymers, is at least of the total.
• such mixed polymerisates will contain between 85-95% of acrylonitrile and the rest one or more of the above or similar components.
• thepolyacrylonitrile in the solution should generally have a molecular weight of at least 40,000, and usually the molecular weight is not higher than about 120,000.
• the preferred molecular weight of the polyacrylonitrile polymers for the purposes of the present invention is between 60,000 and 70,000.
• the polyacrylonitrile is dissolved in aqueous zinc chloride solutions, and it is these solutions which are subjected to the method of the present invention.
• the solutions may contain only zinc chloride as the salt in solution, or it may contain a mixture of zinc chloride with calcium chloride or a mixture of zinc chloride with sodium chloride or a mixture of zinc chloride with magnesium chlo- 3 ride.
• zinc chloride solutions include either solutions of zinc chloride alone or mixed salt solutions of the type indicated above.
• the preferred concentration of the salt in the zinc chloride solutions of the present invention is between 40 and 65% by weight, and most preferably about 5254% by weight.
• a solution containing 60% concentration of the total mixed salt should preferably contain in the case of a mixed salt of ZnCl /CaCl between 35 and 50% of zinc chloride, and most preferably about 40% of zinc chloride which is equal to a ratio of zinc chloride to calcium chloride of 2:1.
• the zinc chloride content should preferably be between 40 and 55%, and most preferably about 45% which is equal to a ratio of zinc chloride to sodium chloride of 3:1.
• the ripening process of the present invention comprises the heating of the zinc chloride-containing polyacrylonitrile spinning solution for some time to achieve lowering of the coagulation point of the solution.
• the heating according to the present invention is carried out at a temperature between 35 and 120 C., preferably at a temperature between 50 and 100 C., and most preferably at a temperature between 60 and 80 C., the most preferred temperature being about 70 C.
• the time of the heating depends upon the particular temperature used.
• the time of heating will be between four days and seven days and at the preferred temperature of 100 C. the time of heating is between 6 hours and 15 hours. At the lower temperature of 35 C. the heating time is correspondingly increased, while at the higher temperature of 120 C. the heating time is correspondingly reduced At the preferred temperature of 6080 C. the heating time is somewhat in between the times given above.
• the present invention is not meant to be limited as to any theory of how or why the ripening process of the present invention achieves the results that it does achieve, the following theory is given in the hopes that it will help others in further investigations in this field. It is believed that because of the weakly acid nature of the solvent, the ripening process of the present invention causes changes in the dissolved polymers possibly to result in a more or less mild saponification of the CN- groups of polymers to amide groups, and to a lesser extent possibly also to carboxyl groups.
• the salt solution used for dissolving the polyacrylonitrile therein be in the slightly acid range, that is that the same have a pH of somewhat less than 7. Most preferably the pH should be between about 4.0 and 5.5. If the salts in the water do not give the desired pH, then the same can be adjusted to be slightly acid by acidification with a mineral acid, most preferably with hydrochloric acid.
• a solution of polyacrylonitrile of molecular weight of 50,00070,000 in a 60% zinc chloride mixed salt solution can be spun in water under about the same conditions if prior to the spinning it is either heated for about 15 hours at 90 C., or about 30 hours at 80 C., for about 72 hours at 70 C., or about 120 hours at 60 C. In all cases approximately the same degree of ripening is achieved.
• the thermal modification should preferably be carried out under milder conditions, for example about 48 hours instead of 72 hours at 70 C.
• the pH value of the solution also has an effect on the specific conditions to be used for the ripening according to the present invention
• the specific conditions in any particular case, for any particular solution can easily be determined by pretesting, and in addition, the present invention provides a special method for determining in any case what is herein referred to as the degree of ripening, which special method can in any case indicate the suitability of the polyacrylonitrile solution for spinning.
• the method of determining the degree of ripeness of spinning solutions according to the present invention is based on the precipitation of polymers in dilute solutions thereof in concentrated salt solutions, the precipitation being achieved by stirring with water.
• Solutions which have not been thermally treated in accordance with the present invention have a ripeness number of between 3.5 and 4.5. Solutions which have been treated thermally for too long a period of time, and which can no longer be used for formation of good quality fibers, have a ripeness number of about 10l2. Between these two values lie the spinning solutions which are most suitable for spinning of good quality fibers in a satisfactory and easily controllable manner. These solutions have ripeness numbers of between 5.8 and 8.0, and most preferably between about 6 and 7. Spinning solutions with ripeness numbers of between 5.5 and 8.0 can be spun in Water to fibers with particularly valuable properties, especially with respect to an unusually high twist strength.
• fibers spun from such solutions exhibit a peculiar shrinking quality.
• such fibers or fiber cables from solution having a ripeness number of 8-9 shrink at temperature above C., for example in water at C. or glycol at C. to a very great extent, in the extreme case to of its original length.
• the fiber or fiber cable remains so thermoplastic that it can be stretched to its original length without sticking, and upon cooling remains at the length.
• it is again introduced into the shrinking bath, it again shrinks to its original shrunk length.
• the shrinking characteristic and the strength and tension properties can be changed, the plastic properties of the fibers under heat however remaining.
• copolymers have a greater tendency towards shrinking than the pure polymerisates.
• the method of the present invention is in general ap plicable to all types of polyacrylonitrile solutions and all concentrations of such solutions. In general, however, it is preferred to use polyacrylonitrile solutions of between about 7 and 14% concentration, and most preferably of about 10% concentration.
• EXAMPLE 1 A pure polyacrylonitrile polymerisate having a molecular weight of 58,000 is worked up into a spinning solution which contains polymer, 54% salt and 36% water by means of a 60% aqueous zinc chloride-calcium chloride solution (2:1). This solution is treated for 3 days in a drying chamber at 70 C., cooled to room temperature, and using the determination method given above is found to have a ripeness number of 6.3.
• the solution is spun through a 400 hole nozzle made of tantalum with the holes having a diameter of 0.25 mm. each.
• Tap water at C. is used as-the precipitation bath, in which the fiber bundle can be very well drawn with a precipitation stretch of 8 cm. and a drawing speed og 3.5 meters per minute.
• the output volume amounts to 41 cc./min., corresponding to 6.1 g. of polyacrylonitrile per minute.
• the bundle After passing throughvarious washing baths, of which the first consists of salt solution, the second 10% salt solution and the third and fourth water, the bundle is stretched in boiling water in a ratio of 1:6.6, passed through a drying cylinder heated to 50 C., and finally wound onto a spool with a final drying speed of 24 meters per minute. Its moisture content amounts to 35% P 0.
• a portion of thus treated bundle is introduced into a shrinking bath of glycol at 170 C. and maintained in the bath for 1 minute. This results in an additional shrinking of 32%, whereby the bundle becomes yellow in color.
• the individual titer now amounts to 15.1 denier.
• the fiber is afterwards as before very well curled and supple and exhibits a tension of 88%.
• the cross section of the thus produced fibers have a round form, as do fibers of non-thermally treated spinning solutions, however, in contrast to fibers from non- 6 thermally treated spinning solutions the fibers according to the present invention are finely serrated on the periphery thereof. These fibers of the present invention are more suitable for coloring by dyeing than fibers spun in the normal manner from zinc chloride solutions.
• the same if quickly taken from the bath, can still in hot condition be stretched to its original length or more. If the thus stretched fibers are again introduced into the shrinking bath, the same shrink to the same extent as before, and this procedure can be repeated indefinitely.
• a shrinking bath for example water of C.
• EXAMPLE 2 A copolymer of 94% acrylonitrile and 6% acrylic acidmethyl ester, having a molecular weight of 55,800 is worked up as in Example 1, with a zinc chloride mixed salt solution (ZnCl /CaClin a ratio of 2:1) to a 10% solution and ripened according to the present invention for 3 days at 70 C. until a ripeness number of 6.9.
• the solution is spun through a 400 hole tantalum nozzle, each hole having a diameter of 0.25 mm., at an output volume of 41 cc./rnin. using a drawing tension of 3.5 meters per minute at the nozzle, the spinning being in water of 15 C. and using a precipitation stretch of 7 cm.
• the resulting fiber After the previously described procedure (hot Water stretching 1:6.6, drying drum 50 C., final draw 24 meters) the resulting fiber has a moisture content of 43% and is wound on spools. The resulting fiber has a good open lustrous appearance, is soft and pliable. The individual fibers have a titer of 6.8, and upon introduction into boiling water shrink 38% and introduction into glycol at C. shrink 79%.
• the properties of the shrunk fiber are similar to the fiber of Example 1.
• the relative winding strength in this case is still higher than in Example 1.
• the elasticity characteristics of the fibers upon heating is the same as in Example 1.
• the values are set forth in Table II below.
• Example 2 The copolymer solution of Example 2 is heat treated for 5 days at 60 C. (instead of for 3 days at 70 C. as in Example 2) thereby obtaining a ripeness number between 6 and 7.
• the ripeness number actually amounts to 6.1.
• the spinning conditions are the same as in Example 2 (3.5 meter nozzle draw, stretching 1:6.6, final draw of 24 meters).
• the wound fibers have a moisture content of 63%, shrink upon drying without tension in air at 4.3%, and is lightly curled and well opened.
• a pure polyacrylonitrile polymerisate, as in Example 1, is worked up to a spinning solution.
• Example 2 Water at a temperature of C. is suitable as the precipitation bath, the precipitation stretch amounting to 10 cm.
• the fibers After passing through the washing baths, as in Example 1, the fibers are stretched in boiling water in a ratio of 116.6, conducted through a drum heated at 70 C., and wound onto spools with a final drying speed of 38 meters per minute. The moisture content amounts to 81% H O. Upon drying in air without tension the fiber shrinks 1.6%. The fiber is practically uncurled, smooth, fairly lustrous and supple. The individual fibers have an individual titer of 11.4 and shrink in boiling water an additional 72.3%, resulting in a very strong curling or crimping. 0
• the individual titer of the thug shrunk fiber now amounts to 41, the tension approximately 60%. If the same fiber is heated for 1 minute in glycol at 170 C. it further shrinks an additional 16.9%, so that the total shrink amounts to 91%. This shrink is obtained if the nonshrunk fiber, without previous shrinking in hot water, is directly immersed in the glycol bath at 170 C. As a result of this treatment the fiber mass becomes intensively yellow colored.
• the fiber piece which has shrunk from 100 cc. to 9 cc. is taken out of the hot shrinking bath and directly stretched, it can be stretched to its original length, without the individual fibers sticking together, and it solidifies upon cooling to this length (approximately 120 cm.).
• the fiber again shrinks together to a length of 9 cm.
• EXAMPLE 5 A pure polyacrylonitrile polymerisate having a molecu- G0 lar weight of 58,000 is brought into an aqueous solution of pure zinc chloride such that the final homogeneous spinning solution contains 10% polymer, 53% zinc chloride and 37% water.
• This solution is subjected to a temperature of 70 C. in a heating chamber until a ripeness number of 6.4 is obtained. This condition is obtained in hours.
• the solution is cooled to room temperature and then spun through a 400 hole tantalum nozzle having a hole diameter of 0.25 mm. into a precipitation bath which consists of water at about 15 C.
• the solution is drawn at an output of 36 cc./ min. from the nozzle, and at a precipitation stretch of 4 cc., and drawn from the bath at a speed of 3.5 meters per minute.
• the fiber bundle is freed of salt in several washing baths and then stretched in 7 boiling water in a ration of 1153. At a drawing speed of 18 meters per minute, the fibers are passed in several windings over a drying drum heated at 50 C. so that the fiber winding on the subsequently placed spool winding arrangement has a moisture content of 33%.
• the fiber bundle is shiny, well opened, without sticking, the individual fibers have a titer of 7.6 denier, and it shrinks upon drying in air without tension to an extent of 2%. An additional shrinking of 42% occurs in boiling water, whereby the individual titer increases to 12.6 denier and the fibers obtain a high degree of curling.
• the fibers moreover possess a high tension with good tear strength, and unusually high winding strength.
• EXAMPLE 6 This example illustrates the determination of the ripeness number in accordance with the present invention.
• Example 1 After subjecting the spinning solution of Example 1 to a heat treatment for 3 days at 70 C., 2 g. of the spinning solution are introduced into a small tube.
• the spinning solution in the tube is diluted with 10 cc. of a 60% solution of zinc chloride-calcium chloride in a ratio of 2: 1.
• the tube is shaken to form a homogeneous solution.
• Method of improving the spinnability of polyacrylonitrile solutions which comprises subjecting a spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylonitrile composed of at least by weight of acrylonitrile units, dissolved in an aqueous 9 zinc chloride solution to a heat treatment at a temperature of between about 35 C. and 120 C., and terminating said heat treatment when the addition under stirring of between about 5.5 and 8.5 cc. of water to 2 g. of said spinning solution diluted with cc. of said aqueous zinc chloride solution causes the resulting solution to become turbid; and spinning the thus treated spinning solution.
• Method of improving the spinnability of polyacrylonitrile solutions which comprises subjecting a spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylon'itr-ile composed of at least 85% by weight of acrylonitrile units, dissolved in an aqueous zinc chloride solution, said solution having a pH of between about 4.0 and 5.5, to a heat treatment at a temperature of between about 50 C. and 120 C., and terminating said heat treatment when the addition under stirring of between about 5.5 and 8.5 cc. of water to 2 g. of said spinning solution diluted with 10 cc. of said aqueous zinc chloride solution causes the resulting solution to become turbid; and spinning the thus treated spinning solution.
• a spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylon'itr-ile composed of at least 85% by weight of acrylonitrile units, dissolved in
• Method of improving the sp'innability of polyacrylonitrile solutions which comprises subjecting a spinning solution consisting essentially of at least one polymer selected from the group consisting of 'polyacrylonitrile and copolymers of poly-acrylonitrile composed of at least 85% by weight of acrylonitrile units, dissolved in an aqueous solution of a salt selected from the group consisting of zinc chloride, a mixture of zinc chloride and calcium chloride in which the Zinc chloride constitutes at least about 50% by weight of the mixture, a mixture of zinc chloride and magnesium chloride in which the zinc chloride constitutes at least about 50% by weight of the mixture, and a mixture of zinc chloride and sodium chloride in which the zinc chloride constitutes at least 60% by weight of the mixture, said solution being in slightly acidic pH range, to a heat treatment at a temperature of between about 50 C.
• a spinning solution consisting essentially of at least one polymer selected from the group consisting of 'polyacrylonitrile and copolymers of poly
• Method of improving the spinnability of polyacrylonitrile solutions which comprises subjecting a spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylonitrile composed of at least 85% by weight of acrylonitrile units, dissolved in an aqueous solution of a salt selected from the group consisting of zinc chloride, a mixture of zinc chloride and calcium chloride in which the zinc chloride constitutes at least about 50% by weight of the mixture, a mixture of zinc chloride and magnesium chloride in which the zinc chloride constitutes at least about 50% by weight of the mixture, and a mixture of zinc chloride and sodium chloride in which the zinc chloride constitutes at least 60% by weight of the mixture, said solution containing between about 40 to 65% by weight of said salt and being in slightly acidic pH range, to a heat treatment at a temperature of between about 50 C.
• a spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers
• Method of improving the spinnability of polyacrylonitrile solutions which comprises subjecting an approximately 714% by weight spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylonitrile composed of at least 85% by weight of acrylonitrile units, dissolved in an aqueous zinc chloride solution, said solution containing between about 40 and 65% by weight of Zinc chloride and being in slightly id acidic pH range, to a heat treatment at a temperature of between about 50 C. and 100 C., and terminating said heat treatment when the addition under stirring of between about 5.5 and 8.5 cc. of water to 2 g. of said spinning solution diluted with 10 cc. of said aqueous zinc chloride solution causes the resulting solution to become turbid; and spinning the thus treated spinning solution.
• Method of improving the sp-innability of polyacrylonitrile solutions which comprises subjecting an approximately 714% by weight spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polya-crylonitrile composed of at least by weight of acrylonitrile units, and having a molecular weight of be tween about 40,000 and 120,000 dis-solved in an aqueous solution of a salt selected from the group consisting of zinc chloride, a mixture of zinc chloride and calcium chloride in which the Zinc chloride constitutes at least about 50% by weight of the mixture, a mixture of zinc chloride and magnesium chloride in which the zinc chloride constitutes at least about 50% by weight of the mixture, and a mixture of zinc chloride and sodium chloride in which the zinc chloride constitutes at.
• a salt selected from the group consisting of zinc chloride, a mixture of zinc chloride and calcium chloride in which the Zinc chloride constitutes at least about 50% by weight of the mixture
• Method of improving the spinnability of polyacrylonitrile solutions which comprises subjecting a spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylonitrile composed of at least 85% by weight of acrylonitrile units, dissolved in an aqueous zinc chloride solution to a heat treatment at a temperature of between about 35 C. and C. until said solution [has a ripeness number of between 5.5 and 8.5, the ripeness number being the number of cubic centimeters of water required to cloud 2 grams of said spinning solution diluted with 10 cubic centimeters of said aqueous zinc chloride solution; and spinning the thus treated spinning solution in water at approximately room temperature.
• Method of improving the spinnability of polyacrylonitrile solutions which comprises subjecting an approximately 744% by weight spinning solution consisting essentially of at least one polymer selected from the group consisting of polyacrylonitrile and copolymers of polyacrylonitrile composed of at least 85% by weight of acrylonitrile units and 'having a molecular weight of between about 40,000 and 120,000 dissolved in an aqueous solution of a salt selected from the group consisting of Zinc chloride, a mixture of Zinc chloride and calcium chloride in which the zinc chloride constitutes at least about 50% by weight of the mixture, a mixture of zinc chloride and magnesium chloride in which the zinc chloride constitutes at least about 50% by weight of the mixture, and a mixture of zinc chloride and sodium chloride in which the zinc chloride constitutes at least 60% by weight of the mixture, said solution containing between about 40 and 65% by weight of said salt and being in slightly acidic pH range, to a heat treatment at a temperature of between about 50 C.
• a salt selected from the

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  • BE BE633778D patent/BE633778A/xx unknown
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• 1962
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• 1963
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